The present invention relates to a detection device comprising a photovoltaic diode array.
Numerous detection systems, such as, for example, the charged coupled device (CCD) type detection system employing parallel scanning, comprise a basic module formed from an array of detector elements, for example, 128 HgCdTe photovoltaic diodes, when the detection takes place in the infrared wavelength range.
Parallel scanning involves causing a mirror to pivot in front of the diode array and the scene to be scanned, which may be for example, a landscape, so as to obtain the same result as if each of the diodes itself pivoted and scanned a line of this landscape. The output signals of the diodes are multiplexed before being fed to a processing circuit.
To ensure that there is no blank line in the video image downstream of the multiplexer, it is required that none of these diodes be defective.
The diode arrays in question are obtained from a wafer. In the case of a HgCdTe semiconductor crystal, several tons of these arrays may be obtained in each wafer. But, the efficiency has always been poor, despite some ten years or more of efforts in this art. This efficiency, i.e., the ratio between the numbers of arrays without defect and the total number of arrays of the wafer, has always been less than 10%. The material loss has then always been considerable. Furthermore, the selection of the non-defective arrays of a wafer has always been done manually, thus adding substantial labor costs to the material costs.
The cost of the above-mentioned detection systems has always therefore been very high, and the present invention aims at reducing the cost.